1. Field of the Invention
The invention relates to a system for determining whether or not a relay is fixed.
2. Description of Related Art
A battery pack is connected to an electrical apparatus (including a load) by a positive electrode line and a negative electrode line. The positive electrode line and the negative electrode line are each provided with a relay. The battery pack and the electrical apparatus can be connected to or disconnected from each other by switching these relays ON and OFF.
Each of the relays has a movable contact point and a fixed contact point, wherein the movable contact point could get fixed to the fixed contact point. When this happens, the relay with its movable contact point fixed to its fixed contact point, stays ON. In this situation, it is needed to be determined that whether or not such relay fixation occurs. For instance, in order to determine fixation of a specific relay out of a plurality of relays, the specific relay is turned OFF, while the rest of the relays are turned ON. The fact that the specific relay is fixed and remains ON can be determined by detecting, with a current sensor or a voltage sensor, that the battery pack and the electrical apparatus are connected to each other.